Brake-testing machine



Dec. l5, 1925 y 1,565'717.

. PfJ. D'ONAVAN n* BRAKE TESTING MACHINE Filed Feb. 19, 1925 2sheets-sheer 1 5 am] mm1 mi@ g4 @im ,i uw@ T Pmi] J waua/a.

Dec. l5, 1925". 1,565,717

- P. J. DoNAvAN BRAKE TESTING MACHINE Filed Feb. 19, 1925 2 Sheets-Sheet2 gnve'noo Paul .Z Donal/an.

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Patented Dec. 15, 1925.

UNITED STATES PATENT OFFICE.

PAUL J.DONAVAN, OF LOS ANGELES, CLIFORNIA.

BRAKE-TESTING MACHINE.

Application med 'February is, 1925. .serial No; 10,222.

To all whom 'it may concern.' 1

Be it known that I, PAUL J. DoNAvAN, a

citizen of thc-United States of' America, re-

siding at Los Angeles, in the county of Los IAngeles and State ofCalifornia, have in' vented certain newand useful Improvements inBrake-Testing Machines; and I do declare the following to be a full,clear, and

exact description of the invention, such as will enable others skilledinl the art to which` kit appertains to make -and use the same,reference being had to the accompanying drawings, and to the charactersof reference marked thereon, whichf'orm a part of this specification.

. This invention relates to improvements in brake testing machines ofthe type disclosed.

' 25 manner. It has hithertol been very difficult to obtain any reliabledata on the action of the brakes with thev result that they .were leftseverely alone until some* emergency arose that showed the driver thathis-brakes were defective. It is now possible by means of the improvedtesting machine described in the above referred to patent, to determineVquite accurately the effectiveness of the brakes of any car and toadjust the brakes on each wheel so as to render them equally effective.

It is the object of this invention tomodif-y the construction describedand claimed in the above referred topatent to such ex- 0 tent that thedesiredv tests may be quickly and conveniently made and which shall alsobe provided with means for determining the force necessary to slide thetires on the supporting surface. This is quite desirable for 5 thereason that when this is known the 'brakes may be adjusted so that theywill afford the greatest possible retardingA effect,

The above and'other objects that will become apparent as the descriptionproceeds are attained bv means which Iwill now proceed to describe indetail, reference for-this purpose being had to the accompanyingdrawings in which:

Fig. 1 Vis a 'plan view of my improved testing machine, arts thereofbeing broken away to better dlsclose the construction.

Fig. 2 is 'a side elevation of the parts shown in Fig. 1, this viewbeing taken along line 2 2. i

Fig. 3 'is a section of one of the shaft couplings taken on line 3 3Fig. 1.

Fig. 4l is a'section taken on line 1 -4,

Fig. 1. j

Fig. 5 is a view, partly in section, showing the manner in which thetractive force between the wheel and its supporting surface can bemeasured. fv

Fig. 6 is a'view similar to Fig. 5 and shows a modified form ofapparatus.

Fig. 7 is 'a section taken on line 7 7, j

Fig. 6.

Fig. -8 is a diagrammatic side elevation showing how the rollers may beprovided with asupporting belt, and

Fig. 9 is a view similarto that in Fig. 8, but showing a modified formof belt.

My device 1s constructedv in the manner shown in Fig. 1 and may haveparts thereof bolted to the supporting foundations 1, the motor 2 fromwhich the power is derived being securedpto the foundation blocklSecured tothe foundations 1 are pillow blocks 4 and 5. Rotatablymounted in proper bearings in blocks 4 and 5 'so as to turn aboutparallel axes are rollers G, each of .which has rigidly securedto oneend a gear wheel 7 that meshes with the pinions 8 which are nonrotatablyconnected to the hollow shafts 9. Secured to the other end of' each ofthe shafts 9 is a cylindrical casing 1() that is provided with aremovable coverv 11. J ournaled Iin the hub 12 kof the cover 11 is ashaft 13. These shafts corres ond to the rear axle shafts of an automoile and extend in opposite directions from a differential housing 14that contains x A shafts 13 to shafts 9. This means will now reading ofthe scale.

be described and for this purpose reference will be had moreparticularly to Figs. 3 and 4. If we bear in mind that the shaft 13 isrotatable in the hub 12, while the circular casing 10 and cover 11 arenonrotatably secured to the shafts 9, the manner in which the power istransmitted will be readily understood. From Fig. 4 it will be notedthat a bell crank lever having arms 18 and 19 is secured to the end ofthe shaft 13. The casing has a lug 20 that serves' as an anchor for oneend of the tension spring 21, the other end of which is secured to theouter end of the arm 19. The shaft 13 tends to rotate the arms 18 and 19in the direc-tion of the arrow 22. A spring 23 may. if desired, besecured to the inner wall of casing 10 bymeans of a clamp 24. flhisspring otl'ers a resistance to rotation` of arm 18 but is not anessential element in this combination, its function being merely toreduce the tension in the rope 25. The rope 25 is fastened to the outerend of arm 18 and passes around a pulley 2G that is rotatably connectedto the casing 10; this rope also passes over the pulleyl27 and throughthe hollow shaft 9 and has it; outer end connected to the spring scale28 by means of a swivel 29. The. scale' is anchored to a stationarymember by some means such as that indicated by numeral 30. It is nowevident that if we apply a force tending to rotate the shaft 13 in thedirection of the arrow 22 that this force. will transmit a torque to thecasing l() through the action of the cable The force will produce atension in the cable and the value of this tension will be measured bythe scale 28. lt' some means is applied to the rollers (i to causefriction or to interfere with their free rotation a greater amount oftorque will-be necessary to rotate them and this requires a greatertension .in the cables which increases the ly means of the band brakes`16 it is possible to stop the rotation of either kone of the shafts 13which feature is taken advantage of in obtaining a comparative readingfor the two wheels in a manner to be hereinafter described.

Let us now describe the operation of the device shown in 1 to 4. liet ussuppose that the wheel 31 in Fig. 2 represents one of the rear wheels ofan automobile and that power is applied tendin to rotate the rollers 6in a clockwise irection'. 'lhe force in the cables 25 can be determinedh v reading the scale 28. lf the brakes are now applied to the wheelsthe tension in,the

cables 25 will increase, a point will soon be reached where the maximumett'ect of the brake is exerted and the reading of the scale for thispoint noted. lf the brakes on the two wheels are not adjusted alike. onewheel may stop rotating before the other one. To obtain the sameadjustment for both wheels, one or the other of the band brakes 17 maybe operated to lock thc shaft 13, after which the reading correspondingto the effectiveness of the. brake for the rotating wheel may bedetermined. By this means the brakes may readily be adjusted so as to beequally effective.

It is evident that the friction between the wheel and the ground is thething that limits the action of the brake and it is not necessary nordesirable to have brakes that will lock the wheels against rotation. Theideal condition is Where the brakes will exert the greatest possibleforce without causing the wheel to stop turning.

It is my intention to first measure the force that is required to slidethe wheels on the supporting surface and then to ad just the brakes sothat they will resist a force-almost equal to this. I accomplish thisadjustment in the following manner:

Referring more particularly to Fig. 5, it will be noted that I haveprovided a plank 32 with a row of pins 33 that project downwardly andengage with the holes 34: in the rollers 6, thereby producing a rack andpinion effect. The wheel 31 rests upon the plank 32 and is anchored to astationary member 35 by means of a chain 36. The motor 2 is now operatedand sutiicient current applied thereto to produce the necessary force tomove the plank 32 in the direction of the arrow 37. The value of thisforce is determined by reading the scale 28. The wheel is noir adjustedas in lfig. 2 and the brakes adjusted until substantially the samereading is obtained. ln ltigs. o and T. l have shown how a channel iron3h' with a board 39 attached may bc substituted for the plank 32.Instead of the row of pins 33, a rack 4-0 may be attached. 'lhis rackengages with the gear wheels 7. lnstead ot' the arrangement shown inFigs. and 7. l may apply an endless belt 41 to the rollers as indicatedin Fig. 8. letter results will be obtained if the belt instead of beingmade from flexible material is made of a number of flat plates or boards1-2 hinged at 43. 'lhc hinges may be provided with lugs 44 that engagethe teeth on wheels 7. 'lo support the. weight of the automobile wheelwithout subjecting the belt 42 to too great a strain l provide a supportwhich l have shown as an l beam 45. Rollers ttl are 'secured to the topof thisl beam. 'lhese rollers engage the lower surface of the belt i2 inthe manner shown.

l'nstcad of using a rack or its equivalent.

. means associated with each pair of rollers.

a plurality of pins on the support as shown in full lines in Figs. 5 and6, I may merely attach one end of a cable C (indicated by dotted linesin Fig. l) to the pulley and the other to the support in the mannershown.

It is evident from the above description that I have produced a testingmachine by means of which the effect of the brakes can be readilydetermined for each wheel and in which the slipping resistance betweenthe tire surface and the support upon which it rests may be readilydetermined.

Having now described my invention what I claim as new is:

1. In a machine for testing automobile brakes, in combination, twospaced pairs of rollers, said rollers being rotatable about parallelaxes, each pair being adapted to support one of the rear wheels of anautomobile, a source of power, means for con'- necting the source ofpower to the rollers for the purpose of rotating the rollers in thesame. direction, said connecting means comprising, a differentialmechanism having two axially aligned shafts adapted forl independentrotation, means for connecting each of said shafts to a pair of rollers,a brake mechanism applied to each of said shafts and a dynamometerbetween each brake mechanism and the corresponding set of rollerswhereby the power transmitted to each set of rollers may be measured. t

2. In a machine for testing automobile brakes, in combination, twospaced pairs of rollers, said rollers being) rotatable about parallelaxes, each pair eingl adapted to support one of the rear wheels of anautomobile, a source of power, means for connecting the source of powervto the rollers for the purpose of rotating the rollers in the samedirection, said connecting'means comprising a differential mechanismhavtwo axially aligned shafts adapted for ,in e

4 pendent rotatiommeans for connecting each of said shafts to a pair ofrollers, a brakey mechanism applied-,to each ofv said shafts, adynamometer between each brake mechanism and the corresponding set ofrollers whereby the power transmitted to each set of rollers may bemeasured and for supporting an automobile wheel.

3. In a machine for testing automobile brakes, in combination, twospaced pairs of rollers, said rollers being rotatable about parallelaxes, each pair being adapted to support one of the rear wheels of anautomobile, a source of power, means for connecting the source of powerto the roller for the purpose of rotating the rollers in the samedirection, said connecting means' comprising a differential mechanismhaving two axially aligned shafts adapted for independent rotation,means for connecting each of said shafts to a pair of rollers, a

brake mechanism applied to each of said shafts, a dynaniometer betweeneach brake mechanism and the correspondinof set of' rollers whereby thepower transmitted to each Set of rollers may be measured and meansassociated with each pair of rollers for supporting an automobile wheel,said means being connected to the rollers by means that prevent thesupporting means from sliding on the rollers.

4. In a machine for testing automobile brakes, in combination, twospaced-pairs of rollers, said rollersibeing rotatable about parallelaxes, each pair being adapted to support one of the rear wheels of anautoinobile, a source of power, means for`connecting the source of powerto the rollers for the purpose of rotating the rollers in the samedirection,msaid connecting means comprising a differential mechanismhaving two axially' aligned shafts adapted for independent'rotation,means for connecting each of said shafts to a pair of rollers` meanscomprising a brake mechanism -for stopping the rotation of either set ofrollers and a dynamometer between the differential and each set ofrollers for measuring the torque exerted by the driving apparatus in itsattempt to rotate the rollers.V

each of said shafts to a pair of rollers,`

means com rising a brake mechanism for stoppingl t e rotation of eitherset of rollers a dvnainometer between the differential and each set ofrollers for measuring the torque exerted by the driving apparatus in itsattempt to rotate the rollers, said dynamoineter comprising a casinginterposed between the ends of a two part shaft, said casing being non-vrotatably connected to one of said shafts and rotatably connected `tothe other shaft,

a crank arm located within the casing, said arm being nonrotatablyconnected to the end of the shaft that is rotatably connected to thecasing and a cable connecting the end of said arm to the casing.

6. In a machine for testing automobile brakes, in combination, twospaced pairs of rollers, said rollers bein rotatable about parallelaxes, each pair ing adapted to support one of the rear wheels of anautomobile,k a source of power, means for connecting the source of powerto the rollers llo for the purpose of rotating the rollers in the samedirection, said connecting means comprising a differential mechanismhaving two axially aligned shafts adapted for independent rotation,vmeans for connecting each of said shafts to a pair of rollers, meanscomprising a brake mechanism for stopping the rotation of either set ofrollers, a dynamometer between the differential and each setof rollersfor measuring the torque exerted by the driving apparatus in its attemptto rotate the rollers, said dynamometer comprising a casing interposedbetween the ends of a two part shaft, said casing being nonrotatablyconnected to one of said shafts and rotatably connected to the othershaft, a crank arm located within the casing, said arm beingnonrotatably connected to the end of the shaft that is rotatablyconnected to the casing, a cable connecting the end of said arm to thecasing, and means for measuring the tension in said cable.

7. In a machine for testing automobile brakes, in combination, twospaced pairs of rollers, said rollers being rotatable about parallelaxes, each pair being adapted to support one of the rear wheels of anautomobile, a source of power, means for connecting the source of powerto the rollers for the purpose of rotating the rollers in the samedirection, said connecting means comprising a differential mechanismhaving two axially aligned shafts adapted for independent rotation,means for connecting each of said shafts to a pair of rollers, meanscomprising a brake mechanism for stopping the rotation of either set of'rollers, a dynamometer between the differential and each set of rollersfor measuring the torque exerted by the driving apparatus in its attemptto rotate the rollers, said dynamometer comprising a casing interposedbetween the'ends of a two part shaft, said casing being nonrotatablyconnected to one of said shafts and rotatably connected to the othershaft, a crank arm located within the casing, said arm beingnonrotatably connected to the end of the shaft that is rotatablyconnected to the casing, a cable connecting the end of said arm to thecasing, means for measuring the tension in said cable and spring meansinterposed between said arm and said casing for reducing the strain onthe cable.

In testimony whereoi` I atlix my signature.

PAUL .ll DONAVAN.

